Flashlight bulb mounting

ABSTRACT

A hand torch has a bulb holder 8 of molded plastics material, designed to protect the bulb 19 from damage due to movement of the batteries 14 if the torch is dropped. The bulb holder has an outer wall 9, inner wall 10, forward flange 11 within which is a bulb-holding recess, and radial ribs 12 against which the forward rim 13 of the battery abuts when the battery contact pip 17 touches the bulb center contact spring 16. The ribs 12 are abutments preventing the battery from moving towards the bulb if the torch is dropped. The lens 4 is made of ORAGLASS DR toughened acrylic material.

This invention relates to hand torches and the like.

A typical construction for a hand torch comprises a tubular barrel orbody and a detachable head or cap which incorporates or retains a lens,reflector and bulb holder. One or more cylindrical batteries arecontained in the body, and the uppermost battery makes contact with itscentral contact pip, on the contact stud of the bulb or on a metalcontact of a bulb holder immediately at the rear of the bulb contactstud. The bulb is positively located in the direction towards the frontend of the torch, to locate it accurately relative to the reflector soas to provide a focus beam.

In conventional torches, bulbs are often damaged and made inoperative,by the torch being dropped. Dropping the torch tends to cause thebattery or batteries to shift abruptly along the torch body, and theresulting impact on the rear end of the torch bulb (particularly in thecase of the larger batteries and multi-battery torches) is oftensufficient to make the bulb inoperative, even if a bulb holder contactis present between the battery pip and the bulb contact stud. Even ifthe torch is dropped in such a way as to tend to move the batteries awayfrom the bulb, the bulb is still commonly damaged, because the contactspring provided at the rear end of the torch body reverses the directionof movement of the batteries relative to the body and bulb.

A hand torch is known, in which a shock absorber/abutment is provided asan additional component seated behind the reflector and surrounding thebulb holder, to limit forwards movement of the batteries towards thebulb holder. This construction is expensive and difficult to assemble,both in manufacture and when the user opens the torch to changebatteries or bulbs, because the shock absorber-abutment is a separateloose component which has to be located accurately in position andangular orientation when the torch is assembled or reassembled.

According to one aspect of the present invention, a torch or the like isprovided with a bulb holder, and an abutment/shock absorber integralwith the bulb holder, for limiting movement of the battery or batteriestowards the bulb holder and for absorbing and/or diverting away from thebulb the kinetic energy of any such movement.

Preferably, the shock absorber/abutment is an annular body of plasticsmaterial around the bulb holder proper, against which the forward andrim of the battery or the foremost battery abuts in normal conditions.

Preferably, a central contact is provided in the bulb holder, having aforward portion which makes contact with the contact stud of a bulb whenseated in the holder, and a rear portion which makes contact with thecentral contact tab of the battery when the rim of the latter abuts onthe shock absorber/abutment.

By making the shock absorber/abutment integral with the bulb holder, weensure that it is always correctly placed in the torch when the torch isassembled or reassembled. Production cost is significantly reduced andconvenience in use is enhanced. Furthermore, the preferred form of shockabsorber/abutment, to be described hereinafter, provides enhancedprotection for the bulb, compared with the previous constructiondescribed above.

According to another aspect of the present invention, a lens of a torch,hand lantern or the like is made of a toughened acrylic material, inparticular that known under the trade name OROGLASS DR, manufactured byRohm and Haas.

Compared with existing materials used for such lenses, this material hasexcellent clarity, vastly improved strength and toughness againstimpact, and it can be welded to plastics materials commonly used fortorch and lantern manufacture such as ABS and polystyrene.

A hand torch embodying the present invention is illustrated by theaccompanying drawings, in which:

FIG. 1 is a longitudinal cross section of a hand torch embodying theinvention;

FIG. 2 is a section through the torch on the line B--B of FIG. 1 showinga lens holder and shock absorber unit; and

FIG. 3 is a rear view of the lens holder and shock absorber unit.

The illustrated torch has a tubular body of molded ABS material, withthe conventional contact spring 23 in its rear end and any suitablecontact and switch mechanism. The body is designed to accommodate two orthree conventional cells for example of DURACELL (Registered Trademark)MN 1300 size.

The torch also has a head assembly 2 mounted detachably, for example byscrewthreads on the body 1. Any suitable head construction can be used,the illustrated torch has a head comprising a cap 3 of molded ABS, alens 4 (which may be flat or of any desired shape) seated in the cap,and a reflector 5 of metal or metallized plastic such as metallizedpolystyrene, seated in the cap behind the lens. The rims of thereflector, lens and cap are united for example by sonic welding, solventwelding, adhesives or otherwise, to form a unitary head assembly.

At its rear, the reflector has a neck 6 provided with an abutment 7 forlocating the flange of a conventional pre-focus bulb 19 so that the bulbfilament is correctly placed relative to the reflector.

The lens is made of a toughened acrylic material marketed under thetrade name OROGLASS DR. This material has properties of toughness andclarity which are superior to those of polycarbonate materials used atpresent where toughness is required, is relatively cheap, and can bebonded for example by sonic welding to ABS materials.

Behind the reflector is a lens holder unit 8 of moulded ABS or acetalmaterial. This comprises a cylindrical outer wall 9, an inner wall 10, aflange 11 extending between these and radial ribs 12 integral with theflange and the inner and outer walls. The ribs form abutment surfacesagainst which rests the rim 13 of the foremost battery 14. A centralrecess within the inner wall 10 has in its base 15 a U or V-shaped leafspring contact 16, of which the forward limb contacts the rear contactstud of the bulb, and the rear limb makes contact with the contact pip17 of the battery 14 when the battery rests against the ribs 12. In thisposition, the pip 17 and the rear limb of the contact spring are clearof the base of the recess.

The forward side of the central region of the unit 8, within the innerwall 10, has a projecting collar 20 that locates the rear end of thebulb so that the bulb locating flange is held against the locatingabutment 7.

The unit 8 incorporating the bulb holder is attached to the rear of thereflector in any convenient way, for example by a push fit, bayonet lockring 21 or screwthreads. The unit 8 may be loose relative to the headassembly 2, but we prefer to provide means for attaching it separably tothe head, for ease of assembly and dismantling, and to ensure accuratelocation of the bulb in the reflector.

In normal use, the contact spring at the rear of the body holds theforemost battery 14 against the ribs 12 of the lens holder unit 8, andthe battery pip 17 in contact with the rear limb of the contact 16, thelatter remaining clear of the bottom of the recess 15. Energisation ofthe bulb is controlled by any suitable switch 22 making and breaking acircuit from the contact spring at the rear of the body, to the bodyshell of the bulb through a contact ring 18 heat-staked to the front ofthe flange 11.

If the torch is dropped, the batteries cannot move towards the bulbholder and bulb because the foremost battery is already in contact withthe abutment ribs 12. The batteries may initially move backwards againstthe contact spring, which will then reverse the movement and throw thebatteries forward, however in this case also their movement is limitedby the abutment ribs 12. The energy of the impact is thereforetransmitted directly to the plastics unit 8, which absorbs part of theenergy internally and transmits the remainder to the torch headassembly. None of the impact energy of the batteries can reach the bulbbecause it is all absorbed or diverted by the unit 8 and in particularthe battery pip 17 is always held clear of the base of the recess 15behind the bulb. Damage to the bulb by dropping the torch is thereforesubstantially eliminated.

Since the unit 8 integrally incorporates both the shock-absorbing anddiverting means and the bulb holder proper, and can be a simpleinjection moulded component in the illustrated embodiment, itsmanufacture is simpler and cheaper than the manufacture of a shockabsorbing component and a separate conventional bulb holder. Assembly ofthe torch is also greatly simplified on manufacture, as is dismantlingand reassembly of the torch by a user to change the bulb or batteries.

In the illustrated embodiment the unit 8 operates to divert impactenergy to the head of the torch. Alternatively, the unit 8 could bearranged to divert the energy directly into the torch body. For example,the torch body may be openable at its rear end for changing batteries,the unit 8 and bulb being inserted through the open rear end intoregister with the reflector but in contact with an internal abutment ofthe body. Alternatively, in a torch with a removable head, the unit 8may have an interrupted periphery which can be inserted behind aninterrupted internal flange of the body in the open front body end, bybeing inserted in the body and then rotated to bring its projectingperipheral region behind the body flange, before the head is fitted tothe body. However, it is believed to be particularly convenient to havethe unit 8 transmit the impact energy to the torch head assembly as thisprovides a very simple and effective construction.

What is claimed is:
 1. A portable lamp comprising a lamp body, a bulbholder in the lamp body, a battery space adjacent the bulb holder forcontaining at least one battery cell, and means for limiting relativemovement of the battery cell towards the bulb holder, characterized inthat the bulb holder is a body of plastic material which includes thesaid movement limiting means as an integral part thereof, with said bulbholder and the integral, movement limiting means comprising inner andouter annular walls, a flange integral with and extending radiallybetween a forward portion of the outer annular wall and the innerannular wall, and radial ribs extending rearwardly of the said flangeand being integral with said flange and with the said outer annularwall, and the said movement limiting means extending axially beyond thecentral contact pip of the bulb, whereby said movement limiting means isadapted to be contacted by the adjacent battery cell upon any axialforward movement thereof to divert shock away from said central contactpip of the bulb.
 2. A portable lamp comprising a lamp body, a reflector,a bulb holder in the lamp body and discrete from said reflector, abattery space adjacent the bulb holder for containing at least onebattery cell, and means for limiting relative movement of the batterycell towards the bulb holder, characterized in that the said movementlimiting means is an annular body around the bulb holder proper and saidmovement limiting means and said bulb holder consists of an integralmolding of plastic material, and the forward end rim of the battery cellor foremeost battery cell abuts said annular body in normal conditions,and in which the said annular body comprises an annular outer wall forlocating the said body and bulb holder laterally in the lamp body.